Search for Neutral Minimal Supersymmetric Standard Model Higgs Bosons Decaying to Tau Pairs in pp Collisions at ffiffiffi
p s
¼ 7 TeV
S. Chatrchyan et al.*
(CMS Collaboration)
(Received 9 April 2011; published 8 June 2011)
A search for neutral minimal supersymmetric standard model (MSSM) Higgs bosons in pp collisions at the LHC at a center-of-mass energy of 7 TeV is presented. The results are based on a data sample corresponding to an integrated luminosity of36 pb1recorded by the CMS experiment. The search uses decays of the Higgs bosons to tau pairs. No excess is observed in the tau-pair invariant-mass spectrum.
The resulting upper limits on the Higgs boson production cross section times branching fraction to tau pairs, as a function of the pseudoscalar Higgs boson mass, yield stringent new bounds in the MSSM parameter space.
DOI:10.1103/PhysRevLett.106.231801 PACS numbers: 14.80.Da, 12.60.Jv, 13.85.Qk, 13.85.Rm
The standard model (SM) has been extremely successful in describing a wide range of phenomena in particle phys- ics, and has survived some four decades of experimental testing. However, the only remaining undiscovered particle predicted by the SM, the Higgs boson [1–5], suffers from quadratically divergent self-energy corrections at high en- ergies [6]. Numerous extensions to the SM have been proposed to address these divergences. One such model, supersymmetry [7], a symmetry between fundamental bo- sons and fermions, results in cancellation of the divergen- ces at tree level. The minimal supersymmetric extension to the standard model (MSSM) requires the presence of two Higgs doublets. This leads to a more complicated scalar sector, with five massive Higgs bosons: a light neutral state (h), two charged states (H), a heavy neutral CP-even state (H), and a neutral CP-odd state (A).
The masses of the MSSM Higgs boson states are speci- fied up to radiative corrections mainly by two parameters, usually taken to be the mass of the pseudoscalar state, mA, and the ratio of the vacuum expectation values of the two Higgs doublets, tan. At large tan (greater than about 20–30), the couplings of the Higgs bosons to down-type quarks are approximately proportional totan. As a result, the production cross section for two of the three neutral Higgs bosons can be nearly as large as that for the electro- weak gauge bosons W and Z at a proton-proton collider such as the Large Hadron Collider (LHC). Two main production processes contribute to pp! þ X, where
¼ h, H, or A: gluon fusion through a a b quark loop and direct b b annihilation from the b parton density in the beam protons.
The mass relations among the neutral MSSM Higgs bosons are such that if mA& 130 GeV=c2, at large tan
the masses of the h and A are nearly degenerate, while that of the H is approximately 130 GeV=c2. If mA* 130 GeV=c2, then the masses of the A and H are nearly degenerate, while that of the h remains near130 GeV=c2. The precise value of the crossover point depends predomi- nantly on the nature of the mass mixing in the top-squark states.
This Letter reports a search for MSSM neutral Higgs bosons in pp collisions atpffiffiffis
¼ 7 TeV at the LHC, using a data sample collected in 2010 corresponding to36 pb1of integrated luminosity recorded by the Compact Muon Solenoid (CMS) experiment. This search is similar to those performed at the Tevatron [8] and complementary to the MSSM Higgs search at LEP [9].
The tau-pair decays of the neutral Higgs bosons, having a branching fraction of roughly 10%, serve as the best experimental signature for this search. The b b mode, though it has a much larger branching fraction, suffers from an overwhelming background from QCD processes.
Three final states where one or both taus decay leptonically are used: eh, h, and e, where we use the symbol hto indicate a reconstructed hadronic decay of a .
The central feature of the CMS apparatus is a super- conducting solenoid, of 6 m internal diameter, providing a field of 3.8 T. Within the field volume are the silicon pixel and strip tracker, the crystal electromagnetic calorimeter and the brass or scintillator hadron calorimeter. Muons are measured in gas-ionization detectors embedded in the steel return yoke. In addition to the barrel and endcap detectors, CMS has extensive forward calorimetry. Details of the CMS detector and its performance can be found else- where [10].
CMS uses a right-handed coordinate system, with the origin at the nominal interaction point, the x axis pointing to the center of the LHC, the y axis pointing up (perpen- dicular to the LHC plane), and the z axis along the
*Full author list given at the end of the article.
Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distri- bution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
anticlockwise-beam direction. The polar angle is mea- sured from the positive z axis and the azimuthal angle is measured in the xy plane. We measure the pseudorapidity
of outgoing particles based on their polar angle accord- ing to lnðtan2Þ.
The triggers used to select the events for this analysis are based on the presence of an electron and/or a muon trigger object [11,12]. With increasing instantaneous luminosity, in order to keep the online transverse momentum thresh- olds on electrons lower than those used in offline selec- tions, special triggers requiring the presence of both a lepton and a charged track with an accompanying calo- rimeter pattern consistent with a decaying hadronically were adopted for the ehand hchannels.
The analysis presented here makes use of particle flow techniques which combine the information from all CMS subdetectors to identify and reconstruct individual parti- cles in the event, namely, muons, electrons, photons, and charged and neutral hadrons. The detailed description of the algorithm and its commissioning can be found else- where [13,14]. The particle list is given as input to the jet, tau, and missing transverse energy reconstruction.
The main challenge in the identification of hadronic tau decays is overcoming the large background due to hadronic jets from QCD processes. Hadronic tau decays almost al- ways yield one or three charged pions, plus zero to several neutral pions, depending on the decay mode. The algorithm used here starts with a high-transverse-momentum (pT) reconstructed charged hadron, and combines it with other nearby reconstructed charged hadron and neutral pion can- didates. The algorithm considers all possible combinations of these objects and determines which are consistent with the kinematics of tau decay. Among those, it chooses the most isolated in terms of the presence of nearby recon- structed particles. Requirements on the isolation variables, specific to each final state, determine an operating point in the space of tau identification efficiency versus the jet-to- tau misidentification rate. We optimize the full analysis for best sensitivity by choosing the ‘‘loose’’ operating point of the HPS algorithm [15].
For the hand ehfinal states, we select events with an isolated muon or electron with pT > 15 GeV=c and jj < 2:1, and an oppositely charged h with pT >
20 GeV=c and jj < 2:3. The transverse mass of the
‘ ¼ e, with the missing transverse energy ET, obtained using all reconstructed particles in the event, is defined as MT ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
2p‘TETð1 cosÞ q
, where is the difference in azimuth between the e or and the ET vector. We require MT< 40 GeV=c2, in order to reduce the back- ground from Wþ jets events. For the e final state, we select events with an isolated electron withjj < 2:5 and an oppositely charged isolated muon withjj < 2:1, both with MT > 15 GeV=c and MT< 50 GeV=c2 (to reject WW and tt events), calculated for each lepton separately.
We reject events in which there are more than one e or .
After the above requirements, the trigger requirements have an efficiency of roughly 90% in the three search channels for Z! events.
The observed number of events in each channel appears in TableI. The largest source of events selected with these requirements comes from Z! . We estimate the con- tribution from this process using a detailedGEANT4simu- lation of the CMS detector, with the events modeled by the
POWHEGMonte Carlo generator [16–19]. We determine the normalization for this process based on the number of observed Z! and Z ! events [20].
A significant source of background arises from QCD multijet events and Wþ jets events in which a jet is mis- identified as h, and there is a real or misidentified e or .
The rates for these processes are estimated using the num- ber of observed same-charge events, and cross-checked using the jet-to-tau misidentification rate measured in multijet events. Other background processes include tt production and Z! ee= events, particularly in the eh channel, due to the 2–3% probability for electrons to be misidentified as h [15]. The small fake-lepton back- ground from Wþ jets and QCD for the e channel is estimated using data. TableI shows the expected number of events for each of the background processes. The event generator PYTHIA6[21] is used to model the Higgs boson signal and other backgrounds. TheTAUOLA[22] package is used for tau decays in all cases.
To distinguish the Higgs boson signal from the back- ground, we reconstruct the tau-pair mass using a likelihood technique. The algorithm estimates the original tau three- momenta by maximizing a likelihood with respect to free parameters corresponding to the missing tau-neutrino mo- menta, and subject to all applicable kinematic constraints.
Other terms in the likelihood take into account the
TABLE I. Number of estimated background events in the selected sample, observed number of events, and overall signal efficiency for mA¼ 200 GeV=c2(including all branching frac- tions) for each search channel. Uncertainties include statistics and all systematics, except for those on integrated luminosity or energy scales. The QCD multijet background for the eh final state is the sum of the QCD multijet and þ jet backgrounds.
Process h eh e
Z ! 329 77 190 44 88 5
tt 6 3 2:6 1:3 7:1 1:3
Z ! ‘‘, jet ! h 6:4 2:4 15 6:2
Z ! ‘‘ 12:9 3:5 109 28 2:4 0:3
Z ! ‘‘ 54:9 4:8 30:6 3:1
W ! , ! ‘ 14:7 1:3 7:0 0:7 1:5 0:5 QCD multijet and þ jet 132 14 181 23
WW=WZ=ZZ 1:6 0:8 0:8 0:4 3:0 0:4
Total 557 79 536 57 102 5
Observed 517 540 101
Signal Efficiency 0.0391 0.0245 0.00582
tau-decay phase space and the probability density in the tau transverse momentum, parametrized as a function of the tau-pair mass. This algorithm yields a tau-pair mass with a mean consistent with the true value, and a distribution with a nearly Gaussian shape. The mass resolution is21% at a Higgs boson mass of 130 GeV=c2, to be compared with
24% for the (non-Gaussian) distribution of the invariant mass reconstructed from the visible tau-decay products.
The observed reconstructed tau-pair mass distribution summed over all three channels is shown in Fig.1.
Various imperfectly known or imperfectly simulated effects can alter the shape and normalization of the recon- structed tau-pair invariant-mass spectrum. The main sources of normalization uncertainties include the total integrated luminosity (11%) [23], background normaliza- tions (TableI), Z production cross section (4%), and lepton identification and isolation efficiency (0.2–2.0% depending on lepton type). The tau identification efficiency uncer- tainty is estimated to be 23% from an independent study [15]. The uncertainty due to trigger efficiencies is 0.2% for the h and e channels, and 2.0% for the eh channel.
Uncertainties that contribute to mass-spectrum shape var- iations include the tau (3%), muon (1%), and electron (2%) energy scales, and uncertainties on the ETscale that is used for the tau-pair invariant-mass reconstruction [24]. The ET scale uncertainties contribute via the jet-energy scale (3%) and unclustered energy scale (10%), where the unclustered energy is defined as the energy remaining after vectorially subtracting leptons and objects clustered in jets with pT> 10 GeV=c.
To search for the presence of a Higgs boson signal in the selected events, we perform a maximum likelihood fit to the tau-pair invariant-mass spectrum. Systematic uncer- tainties are represented by nuisance parameters, which we remove by marginalization, assuming a log normal prior for normalization parameters, and Gaussian priors for mass-spectrum shape uncertainties. The uncertainties that affect the shape of the mass spectrum, mainly those corresponding to the energy scales, are represented by nuisance parameters whose variation results in a continu- ous modification of the spectrum shape [25].
The parameter representing the tau identification uncer- tainty affects taus from the Higgs boson signal and the main background, Z! , equally. This effectively allows the observed Z! events to provide an in situ calibra- tion of this efficiency, except for Higgs boson masses near that of the Z. Near the Z mass, the tau identification efficiency uncertainty dominates in the ehand hchan- nels, and the e channel thus provides the greatest sensitivity.
The mass spectra show no evidence for the presence of a Higgs boson signal, and we set 95% CL (confidence level) upper bounds on the Higgs boson cross section times the tau-pair branching fraction (denoted by B) using a Bayesian method assuming a uniform prior in B. The invariant-mass spectrum in Fig. 1 shows the result of a fit with a Higgs boson signal corresponding to mA¼ 200 GeV=c2 present, for B ¼ 8:71 pb, the value above which we exclude at 95% CL.
Figure2shows the observed upper bound on Bas a function of mA, where we use as the signal acceptance model the combined mass spectra from the gg and b b production processes for h, A, and H, and assuming tan ¼ 30 [26]. The plot also shows the one- and two- standard-deviation range of expected upper limits for vari- ous potential experimental outcomes. The observed limits
Events/(20 GeV/c2)
1 10 102 100 200 300 400
tau pair mass (GeV/c2)
0 100 200 300 400
0
Observed Z QCD, tt Z ,EW mA = 200 GeV/c2
CMS 36 pb-1 7 TeV
FIG. 1 (color online). The reconstructed tau-pair invariant- mass distribution on linear (above) and logarithmic (below) scales, for the sum of the eh, h, and e final states, comparing the observed distributions (points with error bars) to the sum of the expected backgrounds (shaded histograms).
The contribution from a Higgs boson signal (mA¼ 200 GeV=c2) is also shown, with normalization corresponding to the 95% upper bound on B.
Observed 95% CL upper bounds
100 100
10
1
200 300 500
mA (GeV/c2) 400
CMS
36 pb-1 7 TeV
Median expected 1σ expected range 2σ expected range
σ(ppφX)B(φ) (pb)
FIG. 2 (color online). The expected one- and two-standard- deviation ranges and observed 95% CL upper limits on Bas a function of mA. The signal acceptance is based on the MSSM model described in the text, assumingtan ¼ 30.
are well within the expected range assuming no signal. The observed and expected upper limits are shown in TableII.
We can interpret the upper limits on B in the MSSM parameter space oftan versus mAfor an example scenario. We use here the mmaxh [27,28] benchmark scenario in which MSUSY¼ 1 TeV=c2, Xt¼ 2MSUSY,
¼ 200 GeV=c2, M~g¼ 800 GeV=c2, M2¼ 200 GeV=c2, and Ab¼ At, where MSUSY denotes the common soft- SUSY-breaking squark mass of the third generation; Xt¼ At = tan the stop mixing parameter; Atand Abthe stop and sbottom trilinear couplings, respectively; the Higgsino mass parameter; M~g the gluino mass; and M2 the SU(2)-gaugino mass parameter. The value of M1 is fixed via the GUT relation M1 ¼ ð5=3ÞM2sinW= cosW. In determining these bounds on tan, shown in Table II and in Fig.3, we have used the central values of the Higgs boson cross sections as a function oftan reported by the LHC Higgs Cross Section Working Group [26]. The cross sections have been obtained from theGGH@NNLO[29,30]
andHIGLU[31] programs for the gluon-fusion process and from theBBH@NNLO[32] program for the b b ! process in the five-flavor scheme, rescaling the corresponding Yukawa couplings by the MSSM factors calculated with FeynHiggs [33]. The gg! cross-section calculations combine the full quark mass-dependent NLO QCD correc- tions [34] and NNLO corrections in the heavy-top-quark limit [29,35,36]. The effect of the theoretical uncertainties is illustrated in Fig. 3. We do not quote limits above tan ¼ 60 as the theoretical relation between cross section andtan becomes unreliable.
The present results exclude a region in tan down to values smaller than those excluded by the Tevatron
experiments [8] for mA& 140 GeV=c2, and significantly extend the excluded region of MSSM parameter space at larger values of mA. Figure 3 also shows the region ex- cluded by the LEP experiments [9].
In conclusion, we have performed a search for neutral MSSM Higgs bosons, using the first sample of CMS data from proton-proton collisions at a center-of-mass energy of 7 TeV at the LHC, corresponding to an integrated lumi- nosity of36 pb1. The tau-pair decay mode in final states with one e or plus a hadronic decay of a tau, and the e
final state were used. The observed tau-pair mass spectrum reveals no evidence for neutral Higgs boson production, and we determine an upper bound on the product of the Higgs boson cross section and tau-pair branching fraction as a function of mA. These results, interpreted in the MSSM parameter space oftan versus mA, in the mmaxh scenario, exclude a previously unexplored region reaching as low as tan ¼ 23 at mA¼ 130 GeV=c2.
We wish to congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC machine. We thank the technical and administra- tive staff at CERN and other CMS institutes, and acknowl- edge support from FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland);
FCT (Portugal); JINR (Armenia, Belarus, Georgia, TABLE II. Expected range and observed 95% CL upper limits
for B as functions of mA, and 95% CL upper bound on tan in the mmaxh scenario described in the text. No bounds on tan above 60 are quoted.
95% CL Upper Limit
mA Expected B (pb) Observed
(GeV=c2) 1 Median þ1 B tan
90 107.75 153.30 227.10 147.74 27.4
100 88.61 127.09 184.17 112.30 29.2
120 42.72 62.48 90.24 39.61 25.2
130 31.97 45.96 67.11 25.40 22.6
140 22.14 32.81 47.30 18.20 23.6
160 13.83 19.70 29.27 11.37 23.8
180 9.95 14.16 23.13 9.78 28.1
200 7.90 11.36 17.61 8.71 33.0
250 5.01 7.54 11.15 5.77 43.4
300 3.77 5.71 8.58 4.36 56.6
350 3.09 4.64 7.04 3.60
400 2.57 3.79 5.39 2.86
450 2.21 3.34 4.77 2.41
500 2.00 2.95 4.18 2.10
CMS
36 pb-1 7 TeV
0 20 40 60
tan
10 30 50
MSSM mh scenario, MSUSY = 1 TeV/c2
100 200 300
mA (GeV/c2)
150 250
max
±1σ theory CMS observed Tevatron LEP CMS expected 95% CL excluded regions
FIG. 3 (color online). Region in the parameter space oftan
versus mAexcluded at 95% CL in the context of the MSSM mmaxh scenario, with the effect of1 theoretical uncertainties shown.
The other shaded regions show the 95% CL excluded regions from the LEP and Tevatron experiments.
Ukraine, Uzbekistan); MST and MAE (Russia); MSTD (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA).
[1] P. W. Higgs,Phys. Lett. 12, 132 (1964).
[2] P. W. Higgs,Phys. Rev. Lett. 13, 508 (1964).
[3] F. Englert and R. Brout,Phys. Rev. Lett. 13, 321 (1964).
[4] G. Guralnik, C. Hagen, and T. Kibble,Phys. Rev. Lett. 13, 585 (1964).
[5] P. W. Higgs,Phys. Rev. 145, 1156 (1966).
[6] E. Witten,Phys. Lett. B 105, 267 (1981).
[7] S. P. Martin, arXiv:hep-ph/9709356; see also references therein.
[8] Tevatron New Physics and Higgs Working Group (CDF and D0),arXiv:1003.3363.
[9] (LEP Higgs Working Group), Eur. Phys. J. C 47, 547 (2006).
[10] S. Chatrchyan et al. (CMS Collaboration), JINST 0803, S08004 (2008).
[11] (CMS Collaboration), CMS Physics Analysis Summary Report No. CMS-PAS-EGM-10-004, 2010.
[12] (CMS Collaboration), CMS Physics Analysis Summary Report No. CMS-PAS-MUO-10-002, 2010.
[13] (CMS Collaboration), CMS Physics Analysis Summary Report No. CMS-PAS-PFT-09-001, 2009.
[14] (CMS Collaboration), CMS Physics Analysis Summary Report No. CMS-PAS-PFT-10-002, 2010.
[15] (CMS Collaboration), CMS Physics Analysis Summary Report No. CMS-PAS-TAU-11-001 (2011).
[16] S. Alioli et al.,J. High Energy Phys. 07 (2008) 060.
[17] P. Nason,J. High Energy Phys. 11 (2004) 040.
[18] S. Frixione, P. Nason, and C. Oleari,J. High Energy Phys.
11 (2007) 070.
[19] S. Alioli et al.,J. High Energy Phys. 06 (2010) 043.
[20] V. Khachatryan et al. (CMS Collaboration), J. High Energy Phys. 01 (2011) 080.
[21] T. Sjo¨strand et al.,J. High Energy Phys. 05 (2006)026.
[22] Z. Wa¸as et al., Nucl. Phys. B, Proc. Suppl. 98, 96 (2001).
[23] (CMS Collaboration), CMS Physics Analysis Summary Report No. EWK-10-004, 2010.
[24] (CMS Collaboration), J. High Energy Phys. Report No. EWK- 10-013, 2011 (to be published).
[25] J. S. Conway, arXiv:1103.0354 [Proceedings of PhyStat 2011 (to be published)].
[26] S. Dittmaier et al. (LHC Higgs Cross Section Working Group)arXiv:1101.0593.
[27] M. S. Carena et al.,Eur. Phys. J. C 26, 601 (2003).
[28] M. S. Carena et al.,Eur. Phys. J. C 45, 797 (2006).
[29] R. V. Harlander and W. B. Kilgore,Phys. Rev. Lett. 88, 201801 (2002).
[30] R. V. Harlander and W. B. Kilgore,J. High Energy Phys.
10 (2002) 017.
[31] M. Spira,arXiv:hep-ph/9510347.
[32] R. V. Harlander and W. B. Kilgore, Phys. Rev. D 68, 013001 (2003).
[33] S. Heinemeyer, W. Hollik, and G. Weiglein, Comput.
Phys. Commun. 124, 76 (2000).
[34] M. Spira, A. Djouadi, D. Graudenz, and P. M. Zerwas, Nucl. Phys. B453, 17 (1995).
[35] C. Anastasiou and K. Melnikov,Nucl. Phys. B646, 220 (2002).
[36] V. Ravindran, J. Smith, and W. L. van Neerven, Nucl.
Phys. B665, 325 (2003).
S. Chatrchyan,1V. Khachatryan,1A. M. Sirunyan,1A. Tumasyan,1W. Adam,2T. Bergauer,2M. Dragicevic,2J. Ero¨,2 C. Fabjan,2M. Friedl,2R. Fru¨hwirth,2V. M. Ghete,2J. Hammer,2,bS. Ha¨nsel,2M. Hoch,2N. Ho¨rmann,2J. Hrubec,2 M. Jeitler,2G. Kasieczka,2W. Kiesenhofer,2M. Krammer,2D. Liko,2I. Mikulec,2M. Pernicka,2H. Rohringer,2
R. Scho¨fbeck,2J. Strauss,2F. Teischinger,2P. Wagner,2W. Waltenberger,2G. Walzel,2E. Widl,2C.-E. Wulz,2 V. Mossolov,3N. Shumeiko,3J. Suarez Gonzalez,3L. Benucci,4E. A. De Wolf,4X. Janssen,4T. Maes,4 L. Mucibello,4S. Ochesanu,4B. Roland,4R. Rougny,4M. Selvaggi,4H. Van Haevermaet,4P. Van Mechelen,4 N. Van Remortel,4F. Blekman,5S. Blyweert,5J. D’Hondt,5O. Devroede,5R. Gonzalez Suarez,5A. Kalogeropoulos,5 J. Maes,5M. Maes,5W. Van Doninck,5P. Van Mulders,5G. P. Van Onsem,5I. Villella,5O. Charaf,6B. Clerbaux,6 G. De Lentdecker,6V. Dero,6A. P. R. Gay,6G. H. Hammad,6T. Hreus,6P. E. Marage,6L. Thomas,6C. Vander Velde,6
P. Vanlaer,6V. Adler,7A. Cimmino,7S. Costantini,7M. Grunewald,7B. Klein,7J. Lellouch,7A. Marinov,7 J. Mccartin,7D. Ryckbosch,7F. Thyssen,7M. Tytgat,7L. Vanelderen,7P. Verwilligen,7S. Walsh,7N. Zaganidis,7
S. Basegmez,8G. Bruno,8J. Caudron,8L. Ceard,8E. Cortina Gil,8J. De Favereau De Jeneret,8C. Delaere,8,b D. Favart,8A. Giammanco,8G. Gre´goire,8J. Hollar,8V. Lemaitre,8J. Liao,8O. Militaru,8S. Ovyn,8D. Pagano,8 A. Pin,8K. Piotrzkowski,8N. Schul,8N. Beliy,9T. Caebergs,9E. Daubie,9G. A. Alves,10D. De Jesus Damiao,10 M. E. Pol,10M. H. G. Souza,10W. Carvalho,11E. M. Da Costa,11C. De Oliveira Martins,11S. Fonseca De Souza,11
L. Mundim,11H. Nogima,11V. Oguri,11W. L. Prado Da Silva,11A. Santoro,11S. M. Silva Do Amaral,11 A. Sznajder,11F. Torres Da Silva De Araujo,11F. A. Dias,12T. R. Fernandez Perez Tomei,12E. M. Gregores,12,c C. Lagana,12F. Marinho,12P. G. Mercadante,12,cS. F. Novaes,12Sandra S. Padula,12N. Darmenov,13,bL. Dimitrov,13
V. Genchev,13,bP. Iaydjiev,13,bS. Piperov,13M. Rodozov,13S. Stoykova,13G. Sultanov,13V. Tcholakov,13 R. Trayanov,13I. Vankov,13A. Dimitrov,14R. Hadjiiska,14A. Karadzhinova,14V. Kozhuharov,14L. Litov,14
M. Mateev,14B. Pavlov,14P. Petkov,14J. G. Bian,15G. M. Chen,15H. S. Chen,15C. H. Jiang,15D. Liang,15S. Liang,15 X. Meng,15J. Tao,15J. Wang,15J. Wang,15X. Wang,15Z. Wang,15H. Xiao,15M. Xu,15J. Zang,15Z. Zhang,15
Y. Ban,16S. Guo,16Y. Guo,16W. Li,16Y. Mao,16S. J. Qian,16H. Teng,16L. Zhang,16B. Zhu,16W. Zou,16 A. Cabrera,17B. Gomez Moreno,17A. A. Ocampo Rios,17A. F. Osorio Oliveros,17J. C. Sanabria,17N. Godinovic,18
D. Lelas,18K. Lelas,18R. Plestina,18,dD. Polic,18I. Puljak,18Z. Antunovic,19M. Dzelalija,19V. Brigljevic,20 S. Duric,20K. Kadija,20S. Morovic,20A. Attikis,21M. Galanti,21J. Mousa,21C. Nicolaou,21F. Ptochos,21
P. A. Razis,21M. Finger,22M. Finger, Jr.,22Y. Assran,23,eS. Khalil,23,fM. A. Mahmoud,23,gA. Hektor,24 M. Kadastik,24M. Mu¨ntel,24M. Raidal,24L. Rebane,24V. Azzolini,25P. Eerola,25G. Fedi,25S. Czellar,26 J. Ha¨rko¨nen,26A. Heikkinen,26V. Karima¨ki,26R. Kinnunen,26M. J. Kortelainen,26T. Lampe´n,26K. Lassila-Perini,26 S. Lehti,26T. Linde´n,26P. Luukka,26T. Ma¨enpa¨a¨,26E. Tuominen,26J. Tuominiemi,26E. Tuovinen,26D. Ungaro,26 L. Wendland,26K. Banzuzi,27A. Korpela,27T. Tuuva,27D. Sillou,28M. Besancon,29S. Choudhury,29M. Dejardin,29
D. Denegri,29B. Fabbro,29J. L. Faure,29F. Ferri,29S. Ganjour,29F. X. Gentit,29A. Givernaud,29P. Gras,29 G. Hamel de Monchenault,29P. Jarry,29E. Locci,29J. Malcles,29M. Marionneau,29L. Millischer,29J. Rander,29
A. Rosowsky,29I. Shreyber,29M. Titov,29P. Verrecchia,29S. Baffioni,30F. Beaudette,30L. Benhabib,30 L. Bianchini,30M. Bluj,30,hC. Broutin,30P. Busson,30C. Charlot,30T. Dahms,30L. Dobrzynski,30S. Elgammal,30
R. Granier de Cassagnac,30M. Haguenauer,30P. Mine´,30C. Mironov,30C. Ochando,30P. Paganini,30D. Sabes,30 R. Salerno,30Y. Sirois,30C. Thiebaux,30B. Wyslouch,30,iA. Zabi,30J.-L. Agram,31,jJ. Andrea,31D. Bloch,31 D. Bodin,31J.-M. Brom,31M. Cardaci,31E. C. Chabert,31C. Collard,31E. Conte,31,jF. Drouhin,31,jC. Ferro,31 J.-C. Fontaine,31,jD. Gele´,31U. Goerlach,31S. Greder,31P. Juillot,31M. Karim,31,jA.-C. Le Bihan,31Y. Mikami,31
P. Van Hove,31F. Fassi,32D. Mercier,32C. Baty,33S. Beauceron,33N. Beaupere,33M. Bedjidian,33O. Bondu,33 G. Boudoul,33D. Boumediene,33H. Brun,33R. Chierici,33D. Contardo,33P. Depasse,33H. El Mamouni,33J. Fay,33 S. Gascon,33B. Ille,33T. Kurca,33T. Le Grand,33M. Lethuillier,33L. Mirabito,33S. Perries,33V. Sordini,33S. Tosi,33
Y. Tschudi,33P. Verdier,33D. Lomidze,34G. Anagnostou,35M. Edelhoff,35L. Feld,35N. Heracleous,35 O. Hindrichs,35R. Jussen,35K. Klein,35J. Merz,35N. Mohr,35A. Ostapchuk,35A. Perieanu,35F. Raupach,35
J. Sammet,35S. Schael,35D. Sprenger,35H. Weber,35M. Weber,35B. Wittmer,35M. Ata,36W. Bender,36 E. Dietz-Laursonn,36M. Erdmann,36J. Frangenheim,36T. Hebbeker,36A. Hinzmann,36K. Hoepfner,36 T. Klimkovich,36D. Klingebiel,36P. Kreuzer,36D. Lanske,36,aC. Magass,36M. Merschmeyer,36A. Meyer,36
P. Papacz,36H. Pieta,36H. Reithler,36S. A. Schmitz,36L. Sonnenschein,36J. Steggemann,36D. Teyssier,36 M. Tonutti,36M. Bontenackels,37M. Davids,37M. Duda,37G. Flu¨gge,37H. Geenen,37M. Giffels,37W. Haj Ahmad,37
D. Heydhausen,37T. Kress,37Y. Kuessel,37A. Linn,37A. Nowack,37L. Perchalla,37O. Pooth,37J. Rennefeld,37 P. Sauerland,37A. Stahl,37M. Thomas,37D. Tornier,37M. H. Zoeller,37M. Aldaya Martin,38W. Behrenhoff,38 U. Behrens,38M. Bergholz,38,kA. Bethani,38K. Borras,38A. Cakir,38A. Campbell,38E. Castro,38D. Dammann,38
G. Eckerlin,38D. Eckstein,38A. Flossdorf,38G. Flucke,38A. Geiser,38J. Hauk,38H. Jung,38,bM. Kasemann,38 I. Katkov,38,lP. Katsas,38C. Kleinwort,38H. Kluge,38A. Knutsson,38M. Kra¨mer,38D. Kru¨cker,38E. Kuznetsova,38 W. Lange,38W. Lohmann,38,kR. Mankel,38M. Marienfeld,38I.-A. Melzer-Pellmann,38A. B. Meyer,38J. Mnich,38
A. Mussgiller,38J. Olzem,38D. Pitzl,38A. Raspereza,38A. Raval,38M. Rosin,38R. Schmidt,38,k T. Schoerner-Sadenius,38N. Sen,38A. Spiridonov,38M. Stein,38J. Tomaszewska,38R. Walsh,38C. Wissing,38
C. Autermann,39V. Blobel,39S. Bobrovskyi,39J. Draeger,39H. Enderle,39U. Gebbert,39K. Kaschube,39 G. Kaussen,39R. Klanner,39J. Lange,39B. Mura,39S. Naumann-Emme,39F. Nowak,39N. Pietsch,39C. Sander,39 H. Schettler,39P. Schleper,39M. Schro¨der,39T. Schum,39J. Schwandt,39H. Stadie,39G. Steinbru¨ck,39J. Thomsen,39
C. Barth,40J. Bauer,40V. Buege,40T. Chwalek,40W. De Boer,40A. Dierlamm,40G. Dirkes,40M. Feindt,40 J. Gruschke,40C. Hackstein,40F. Hartmann,40M. Heinrich,40H. Held,40K. H. Hoffmann,40S. Honc,40 J. R. Komaragiri,40T. Kuhr,40D. Martschei,40S. Mueller,40Th. Mu¨ller,40M. Niegel,40O. Oberst,40A. Oehler,40 J. Ott,40T. Peiffer,40D. Piparo,40G. Quast,40K. Rabbertz,40F. Ratnikov,40N. Ratnikova,40M. Renz,40C. Saout,40
A. Scheurer,40P. Schieferdecker,40F.-P. Schilling,40M. Schmanau,40G. Schott,40H. J. Simonis,40F. M. Stober,40 D. Troendle,40J. Wagner-Kuhr,40T. Weiler,40M. Zeise,40V. Zhukov,40,lE. B. Ziebarth,40G. Daskalakis,41 T. Geralis,41K. Karafasoulis,41S. Kesisoglou,41A. Kyriakis,41D. Loukas,41I. Manolakos,41A. Markou,41 C. Markou,41C. Mavrommatis,41E. Ntomari,41E. Petrakou,41L. Gouskos,42T. J. Mertzimekis,42A. Panagiotou,42 E. Stiliaris,42I. Evangelou,43C. Foudas,43P. Kokkas,43N. Manthos,43I. Papadopoulos,43V. Patras,43F. A. Triantis,43 A. Aranyi,44G. Bencze,44L. Boldizsar,44C. Hajdu,44,bP. Hidas,44D. Horvath,44,mA. Kapusi,44K. Krajczar,44,n F. Sikler,44,bG. I. Veres,44,nG. Vesztergombi,44,nN. Beni,45J. Molnar,45J. Palinkas,45Z. Szillasi,45V. Veszpremi,45
P. Raics,46Z. L. Trocsanyi,46B. Ujvari,46S. Bansal,47S. B. Beri,47V. Bhatnagar,47N. Dhingra,47R. Gupta,47 M. Jindal,47M. Kaur,47J. M. Kohli,47M. Z. Mehta,47N. Nishu,47L. K. Saini,47A. Sharma,47A. P. Singh,47 J. B. Singh,47S. P. Singh,47S. Ahuja,48S. Bhattacharya,48B. C. Choudhary,48P. Gupta,48S. Jain,48S. Jain,48
A. Kumar,48K. Ranjan,48R. K. Shivpuri,48R. K. Choudhury,49D. Dutta,49S. Kailas,49V. Kumar,49 A. K. Mohanty,49,bL. M. Pant,49P. Shukla,49T. Aziz,50M. Guchait,50,oA. Gurtu,50M. Maity,50,pD. Majumder,50
G. Majumder,50K. Mazumdar,50G. B. Mohanty,50A. Saha,50K. Sudhakar,50N. Wickramage,50S. Banerjee,51 S. Dugad,51N. K. Mondal,51H. Arfaei,52H. Bakhshiansohi,52,qS. M. Etesami,52A. Fahim,52,qM. Hashemi,52
A. Jafari,52,qM. Khakzad,52A. Mohammadi,52,rM. Mohammadi Najafabadi,52S. Paktinat Mehdiabadi,52 B. Safarzadeh,52M. Zeinali,52,sM. Abbrescia,53a,53bL. Barbone,53a,53bC. Calabria,53a,53bA. Colaleo,53a D. Creanza,53a,53cN. De Filippis,53a,53c,bM. De Palma,53a,53bL. Fiore,53aG. Iaselli,53a,53cL. Lusito,53a,53b G. Maggi,53a,53cM. Maggi,53aN. Manna,53a,53bB. Marangelli,53a,53bS. My,53a,53cS. Nuzzo,53a,53bN. Pacifico,53a,53b
G. A. Pierro,53aA. Pompili,53a,53bG. Pugliese,53a,53cF. Romano,53a,53cG. Roselli,53a,53bG. Selvaggi,53a,53b L. Silvestris,53aR. Trentadue,53aS. Tupputi,53a,53bG. Zito,53aG. Abbiendi,54aA. C. Benvenuti,54aD. Bonacorsi,54a
S. Braibant-Giacomelli,54a,54bL. Brigliadori,54aP. Capiluppi,54a,54bA. Castro,54a,54bF. R. Cavallo,54a M. Cuffiani,54a,54bG. M. Dallavalle,54aF. Fabbri,54aA. Fanfani,54a,54bD. Fasanella,54aP. Giacomelli,54a M. Giunta,54aS. Marcellini,54aG. Masetti,54aM. Meneghelli,54a,54bA. Montanari,54aF. L. Navarria,54a,54b
F. Odorici,54aA. Perrotta,54aF. Primavera,54aA. M. Rossi,54a,54bT. Rovelli,54a,54bG. Siroli,54a,54b R. Travaglini,54a,54bS. Albergo,55a,55bG. Cappello,55a,55bM. Chiorboli,55a,55b,bS. Costa,55a,55bA. Tricomi,55a,55b C. Tuve,55aG. Barbagli,56aV. Ciulli,56a,56bC. Civinini,56aR. D’Alessandro,56a,56bE. Focardi,56a,56bS. Frosali,56a,56b
E. Gallo,56aS. Gonzi,56a,56bP. Lenzi,56a,56bM. Meschini,56aS. Paoletti,56aG. Sguazzoni,56aA. Tropiano,56a,b L. Benussi,57S. Bianco,57S. Colafranceschi,57,tF. Fabbri,57D. Piccolo,57P. Fabbricatore,58R. Musenich,58 A. Benaglia,59a,59bF. De Guio,59a,59b,bL. Di Matteo,59a,59bA. Ghezzi,59a,59bS. Malvezzi,59aA. Martelli,59a,59b A. Massironi,59a,59bD. Menasce,59aL. Moroni,59aM. Paganoni,59a,59bD. Pedrini,59aS. Ragazzi,59a,59bN. Redaelli,59a
S. Sala,59aT. Tabarelli de Fatis,59a,59bV. Tancini,59a,59bS. Buontempo,60aC. A. Carrillo Montoya,60a,b N. Cavallo,60a,uA. De Cosa,60a,60bF. Fabozzi,60a,uA. O. M. Iorio,60a,bL. Lista,60aM. Merola,60a,60bP. Paolucci,60a
P. Azzi,61aN. Bacchetta,61aP. Bellan,61a,61bD. Bisello,61a,61bA. Branca,61aR. Carlin,61a,61bP. Checchia,61a M. De Mattia,61a,61bT. Dorigo,61aU. Dosselli,61aF. Fanzago,61aF. Gasparini,61a,61bU. Gasparini,61a,61b S. Lacaprara,61aI. Lazzizzera,61a,61cM. Margoni,61a,61bM. Mazzucato,61aA. T. Meneguzzo,61a,61bM. Nespolo,61a,b
L. Perrozzi,61a,bN. Pozzobon,61a,61bP. Ronchese,61a,61bF. Simonetto,61a,61bE. Torassa,61aM. Tosi,61a,61b S. Vanini,61a,61bP. Zotto,61a,61bG. Zumerle,61a,61bP. Baesso,62a,62bU. Berzano,62aS. P. Ratti,62a,62bC. Riccardi,62a,62b P. Torre,62a,62bP. Vitulo,62a,62bC. Viviani,62a,62bM. Biasini,63a,63bG. M. Bilei,63aB. Caponeri,63a,63bL. Fano`,63a,63b
P. Lariccia,63a,63bA. Lucaroni,63a,63b,bG. Mantovani,63a,63bM. Menichelli,63aA. Nappi,63a,63bF. Romeo,63a,63b A. Santocchia,63a,63bS. Taroni,63a,63b,bM. Valdata,63a,63bP. Azzurri,64a,64cG. Bagliesi,64aJ. Bernardini,64a,64b T. Boccali,64a,bG. Broccolo,64a,64cR. Castaldi,64aR. T. D’Agnolo,64a,64cR. Dell’Orso,64aF. Fiori,64a,64bL. Foa`,64a,64c
A. Giassi,64aA. Kraan,64aF. Ligabue,64a,64cT. Lomtadze,64aL. Martini,64a,vA. Messineo,64a,64bF. Palla,64a G. Segneri,64aA. T. Serban,64aP. Spagnolo,64aR. Tenchini,64aG. Tonelli,64a,64b,bA. Venturi,64a,bP. G. Verdini,64a L. Barone,65a,65bF. Cavallari,65aD. Del Re,65a,65bE. Di Marco,65a,65bM. Diemoz,65aD. Franci,65a,65bM. Grassi,65a,b
E. Longo,65a,65bS. Nourbakhsh,65aG. Organtini,65a,65bF. Pandolfi,65a,65b,bR. Paramatti,65aS. Rahatlou,65a,65b N. Amapane,66a,66bR. Arcidiacono,66a,66cS. Argiro,66a,66bM. Arneodo,66a,66cC. Biino,66aC. Botta,66a,66b,b
N. Cartiglia,66aR. Castello,66a,66bM. Costa,66a,66bN. Demaria,66aA. Graziano,66a,66b,bC. Mariotti,66a M. Marone,66a,66bS. Maselli,66aE. Migliore,66a,66bG. Mila,66a,66bV. Monaco,66a,66bM. Musich,66a,66b M. M. Obertino,66a,66cN. Pastrone,66aM. Pelliccioni,66a,66bA. Romero,66a,66bM. Ruspa,66a,66cR. Sacchi,66a,66b
V. Sola,66a,66bA. Solano,66a,66bA. Staiano,66aA. Vilela Pereira,66a,66bS. Belforte,67aF. Cossutti,67a G. Della Ricca,67a,67bB. Gobbo,67aD. Montanino,67a,67bA. Penzo,67aS. G. Heo,68S. K. Nam,68S. Chang,69 J. Chung,69D. H. Kim,69G. N. Kim,69J. E. Kim,69D. J. Kong,69H. Park,69S. R. Ro,69D. Son,69D. C. Son,69 T. Son,69Zero Kim,70J. Y. Kim,70S. Song,70S. Choi,71B. Hong,71M. S. Jeong,71M. Jo,71H. Kim,71J. H. Kim,71
T. J. Kim,71K. S. Lee,71D. H. Moon,71S. K. Park,71H. B. Rhee,71E. Seo,71S. Shin,71K. S. Sim,71M. Choi,72 S. Kang,72H. Kim,72C. Park,72I. C. Park,72S. Park,72G. Ryu,72Y. Choi,73Y. K. Choi,73J. Goh,73M. S. Kim,73 E. Kwon,73J. Lee,73S. Lee,73H. Seo,73I. Yu,73M. J. Bilinskas,74I. Grigelionis,74M. Janulis,74D. Martisiute,74
P. Petrov,74T. Sabonis,74H. Castilla-Valdez,75E. De La Cruz-Burelo,75R. Lopez-Fernandez,75 R. Magan˜a Villalba,75A. Sa´nchez-Herna´ndez,75L. M. Villasenor-Cendejas,75S. Carrillo Moreno,76
